基于渔获物统计的中国近海鱼类营养级结构变换及其与捕捞作业的关系

为了解我国东部海域(渤海、黄海和东海)和南海的鱼类生态结构和渔业资源变化特征,本研究在1983—2013年中国海洋渔船渔获统计数据的基础上,首先将渔获物中的鱼类按照营养级归类,然后计算其平均营养级(TL)和Fi B指数,并结合海洋捕捞作业方式,对鱼类的营养级结构长期变化进行分析。结果表明,在东部海域捕捞的25种主要鱼类渔获中,31年间TL呈现下降趋势,低营养层级鱼类比例增长了60%,中营养层级鱼类比例增长了129%,高营养级鱼类则下降了近51%;而在南海,31年间TL变化不明显,低营养级鱼类比例下降了6%,中营养级鱼类下降了43%,高营养级鱼类增长198%。东部海域和南海的渔获物鱼类生态结构变化说明,就营养级水平而言,东部海域近海渔业资源呈现明显的衰退现象,而南海则还未出现这种现象。

Changes in trophic-level structure of the main fish species caught by China and their relationship with fishing method

The long-term changes in fish ecological structure and fishery resources were studied in the Eastern Seas of China (Bohai Sea,Yellow Sea,and East China Sea) and the South China Sea based on 1983-2013 catch statistical data,using fish trophic level (TL),the FiB index,and the main fish cluster caught by Chinese fishing vessels.A correlation analysis of the change in fish ecological structure based on fishing method was also conducted.The results show that mean TL has declined among the 25 main fish species caught in the Eastern Seas of China.The contribution of carnivorous fish in the lowest class to total catch has increased 60％,the contribution of carnivorous fish in the middle class to total catch has increased 129％,and the contribution of carnivorous fish in the advanced class to total catch has decreased 51％.No changes in mean TL have occurred in the South China Sea;however,the contribution of carnivorous fish in the lowest class to total catch has decreased 6％,the contribution of carnivorous fish in the middle class to total catch has decreased 43％,and the contribution of carnivorous fish in the advanced and middle classes to total catch has increased 198％.These results suggest that fisheries resources in the Eastern Seas of China,but not those in the South China Sea,are declining.